Sustainable Development and Integrated Assessment

by Achim Sydow, Helge Rosé and Waltraud Rufeger

A new research project about sustainable development was initiated
this year by the Hermann von Helmholtz Association of German Research Centers.
In the course of this project at GMD Institute for Computer Architecture
and Software Technology interactive and integrated simulation tools for
complex environment systems modelling will be developed. The integrated
assessment approach to model complex systems on different levels of a hierarchy
is introduced as a possible tool to address questions connected with the
problem of sustainable development and global change.

With the third millennium approaching, the question of sustainable development
is becoming an important concept to investigate different possible scenarios
of our future: Is it possible to realise a development that meets the needs
of the present and as well as those of future generations? This problem
is closely related to the natural resilience and buffer capacity of the
biosphere responding to the impact of human development, ie the question
of global change.

The progress in human development is becoming increasingly dependent
on the environment and may be restricted by its future deterioration. The
problem of global change is complex in nature, represented by various interactions
that operate on different spatial-temporal scales. Addressing these issues
demands an integrative consideration of all relevant interactions between
humans and the environment.

The reductionistic approach has failed in providing an adequate analysis
of complex, large-scale global phenomena. A more promising route seems
to be a more holistic, integrated approach, based on a systems-oriented
analysis, which concentrates on the interactions and feedback mechanisms
between the different subsystems.

Since the 1970s, there is a growing interest in an integrated approach
to the problem of global change, called integrated assessment. In general,
integrated assessment can be defined as an interdisciplinary process of
combining, interpreting and communicating knowledge from diverse scientific
disciplines in such a way that the whole cause-effect chain of a problem
can be evaluated from a synoptic perspective with two characteristics:
it should have added value compared to single disciplinary oriented assessment
and it should provide useful information to decision-makers.

Integrated assessment is an iterative, continuing process, where on
the one hand integrated insights from the scientific community are communicated
to the decision-making community and on the other hand experiences and
learning effects from decision-makers form the input for scientific assessment.
In Europe, integrated assessment has its origins in the population-environment,
ecological and acidification research. In North America the attention was
mainly concentrated on the economic modelling. During the last years, integrated
assessment models have increasingly focused on climate change and sustainable
development.

The main questions under consideration today are: human health management
and population growth, management of fossil fuels and renewable energy
resources, safeguarding of food and fresh water and the stability of the
biogeochemical cycles with respect to the human perturbations.

To model these complex systems, the Pressure-State-Impact-Response concept
may be used as organizing principle for achieving a plausible division
of the cause-effect chains into subsystems. The Pressure System represents
social, economic and ecological driving forces underlying the pressure
onto the human and environmental system.

The State System represents physical, chemical and biological changes
in the state of the biosphere, as well as changes in human population and
resources / capitals. The Impact System represents social, economic and
ecological impacts as a result of human and/or natural disturbance. The
Response System represents human intervention in response to ecological
and societal impacts.

Modern integrated assessment approaches use a hierarchic structure to
overcome the complexity problem of modelling. At the lower level of aggregation,
economy-energy models operate in multi-year time steps with national or
regional political boundaries. Their regional and distributed output data
may be used in theme-specific models like RAINS (Regional Acidification
Information and Simulation) or IMAGE (Integrated Model to Assess the Greenhouse
Effect) at the next level of aggregation. Their results of characteristic
simulations provide a guide line to setting up metamodels which establish
the building blocks for integrated assessment models, eg the TARGETS system
(Tool to Assess Regional and Global Environmental and health Targets for
Sustainability) of the National Institute for Public Health and the Environment,
The Netherlands/RIVM, at the highest level of aggregation.

This hierarchic system of models describes the problem at different
levels of aggregation and integration. Therefore it provides a flexible
framework of simulation tools which can help to answer the multifaceted
questions regarding the understanding and managing of complex environmental
systems. Based on this concept the GMD Institute for Computer Architecture
and Software Technology will develop an interactive and distributed modelling
system which is supposed to tackle questions connected with the problem
of sustainable development.